The present invention relates to testing multiplexing devices.
Testing multiplexing devices, i.e. devices with a plurality of ports (inputs/outputs) on one side and one port (output/input) on the other side, has become increasingly important.
A typical application for such multiplexing devices is a serializer receiving a plurality of parallel data ports and providing therefrom a serialized data stream on one output port. In a sequential and circular manner, the serializer addresses each one of the parallel input ports and provides a portion of the applied data signal of that input port as output to the serialized output port. Thus, parallel data streams can be converted into a serial data stream, whereby typically the data transmission rate at the serialized output of a serializer with n parallel input ports is n-times the data transmission speed of each parallel input port.
Another important application of multiplexing devices are deserializers working in the opposite direction as serializers, so that a serial input stream is deserialized, i.e. converted into a parallel output stream.
Serializer/Deserializer-Devices (SerDes) allow serial/parallel data stream conversion in either way.
In its deserializing mode, multiplexing devices are typically tested by providing a known serial data stream and comparing the received deserialized data pattern at the parallel side with an expected deserialized data pattern. However, for safely comparing actually received with expected data pattern, it is essential to clearly identify data pattern corresponding to the applied data pattern in the received data stream.